Soft-lithographic approach to functionalization and nanopatterning oxide-free silicon

We report a simple, reliable high-throughput method for patterning passivated silicon with reactive organic monolayers and demonstrate selective functionalization of the patterned substrates with both small molecules and proteins. The approach completely protects silicon from chemical oxidation, provides precise control over the shape and size of the patterned features in the 100 nm domain, and gives rapid, ready access to chemically discriminated patterns that can be further functionalized with both organic and biological molecules.     

Drug discovery using very large numbers of patents. General strategy with extensive use of match and edit operations

A patent data base of 6.7 million compounds generated by a very high performance computer (Blue Gene) requires new techniques for exploitation when extensive use of chemical similarity is involved. Such exploitation includes the taxonomic classification of chemical themes, and data mining to assess mutual information between themes and companies. Importantly, we also launch candidates that evolve by “natural selection” as failure of partial match against the patent data base and their ability to bind to the protein target appropriately, by simulation on Blue Gene. An unusual feature of our method is that algorithms and workflows rely on dynamic interaction between match-and-edit instructions, which in practice are regular expressions. Similarity testing by these uses SMILES strings and, less frequently, graph or connectivity representations. Examining how this performs in high throughput, we note that chemical similarity and novelty are human concepts that largely have meaning by utility in specific contexts. For some purposes, mutual information involving chemical themes might be a better concept.     

Highly dispersed palladium(II) in a defective metal-organic framework: application to C-H activation and functionalization

High reversibility during crystallization leads to relatively defect-free crystals through repair of nonperiodic inclusions, including those derived from impurities. Microporous coordination polymers (MCPs) can achieve a high level of crystallinity through a related mechanism whereby coordination defects are repaired, leading to single crystals. In this work, we discovered and exploited the fact that this process is far from perfect for MCPs and that a minority ligand that is coordinatively identical to but distinct in shape from the majority linker can be inserted into the framework, resulting in defects. The reaction of Zn(II) with 1,4-benzenedicarboxylic acid (H(2)BDC) in the presence of small amounts of 1,3,5-tris(4-carboxyphenyl)benzene (H(3)BTB) leads to a new crystalline material, MOF-5(O(h)), that is nearly identical to MOF-5 but has an octahedral morphology and a number of defect sites that are uniquely functionalized with dangling carboxylates. The reaction with Pd(OAc)(2) impregnates the metal ions, creating a heterogeneous catalyst with ultrahigh surface area. The Pd(II)-catalyzed phenylation of naphthalene within Pd-impregnated MOF-5(O(h)) demonstrates the potential utility of an MCP framework for modulating the reactivity and selectivity of such transformations. Furthermore, this novel synthetic approach can be applied to different MCPs and will provide scaffolds functionalized with catalytically active metal species.     

C-H···π interactions in the CHBrF2···HCCH weakly bound dimer

The microwave spectra of four isotopologues of the CHBrF(2)···HCCH weakly bound dimer have been measured in the 6-18 GHz region using chirped-pulse and Balle-Flygare Fourier-transform microwave spectroscopy. Spectra of (13)CH(79)BrF(2) and (13)CH(81)BrF(2) monomers have also been measured, and spectroscopic constants are reported. Measurement of spectra for the (79)Br and (81)Br isotopologues of CHBrF(2) complexed with both (12)C(2)H(2) and (13)C(2)H(2) have allowed the determination of a structure with C(s) symmetry for this complex. CHBrF(2) interacts with the triple bond of acetylene via a C-H···π contact (R(H···π) = 2.670(8) ?) with the Br atom lying in the ab plane, located 3.293(40) ? from a hydrogen atom of the HCCH molecule. The structure of CHBrF(2)···HCCH has been compared with recently studied related acetylene complexes, including a comparison with (and further structural analysis of) the CHClF(2)···HCCH complex.     

The synthesis of dehydrotryptophan and dehydrotryptophan-containing peptides

Dehydrotryptophan and its derivatives are non-proteinogenic amino acids commonly found in peptide-based natural products produced by microorganisms, marine organisms and plants. These non-proteinogenic amino acids are found in secondary metabolites and are formed by post translational modification processes. Although comprehensive reviews on the synthesis of dehydroamino acids are available, this perspective focuses solely on methods to synthesise the dehydrotryptophan-containing segment of naturally occurring peptides, amino acids and their derivatives.     

Bioactive diterpenoid containing a reversible "spring-loaded" (E,Z)-dieneone Michael acceptor

Three new briarane diterpenoids, briareolate esters L-N (1-3), have been isolated from a gorgonian Briareum asbestinum. Briareolate esters L (1) and M (2) are the first natural products possessing a 10-membered macrocyclic ring with a (E,Z)-dieneone and exhibit growth inhibition activity against both human embryonic stem cells (BG02) and a pancreatic cancer cell line (BxPC-3). Briareolate ester L (1) was found to contain a "spring-loaded" (E,Z)-dieneone Michael acceptor group that can form a reversible covalent bond to model sulfur-based nucleophiles.     

Alcohol and metal determination in alcoholic beverages through high-temperature liquid-chromatography coupled to an inductively coupled plasma atomic emission spectrometer

In the present work, an inductively coupled plasma atomic emission spectrometry (ICP-AES) system was used as a high temperature liquid chromatography (HTLC) detector for the determination of alcohols and metals in beverages. For the sake of comparison, a refractive index (RI) detector was also employed for the first time to detect alcohols with HTLC. The organic compounds studied were methanol, ethanol, propan-1-ol and butan-1-ol (in the 10-125 mg/L concentration range) and the elements tested were magnesium, aluminum, copper, manganese and barium at concentrations included between roughly 0.01 and 80 mg/L. Column heating temperatures ranged from 80 to 175 °C and the optimum ones in terms of peak resolution, sensitivity and column lifetime were 125 and 100 °C for the HTLC-RI and HTLC-ICP-AES couplings, respectively. The HTLC-ICP-AES interface design (i.e., spray chamber design and nebulizer type used) was studied and it was found that a single pass spray chamber provided about 2 times higher sensitivities than a cyclonic conventional design. Comparatively speaking, limits of detection for alcohols were of the same order for the two evaluated detection systems (from 5 to 25 mg/L). In contrast, unlike RI, ICP-AES provided information about the content of both organic and inorganic species. Furthermore, temperature programming was applied to shorten the analysis time and it was verified that ICP-AES was less sensitive to temperature changes and modifications in the analyte chemical nature than the RI detector. Both detectors were successfully applied to the determination of short chain alcohols in several beverages such as muscatel, pacharan, punch, vermouth and two different brands of whiskeys (from 10 to 40 g of ethanol/100 g of sample). The results of the inorganic elements studied by HTLC-ICP-AES were compared with those obtained using inductively coupled plasma mass spectrometry (ICP-MS) obtaining good agreement between them. Recoveries found for spiked samples were close to 100% for both, inorganic elements (with both HLTC-ICP-AES and ICP-MS) and alcohols (with both HTLC-ICP-AES and HTLC-RI hyphenations).     

Crystallization and characterization of an inflammatory lectin purified from the seeds of Dioclea wilsonii

DwL, a lectin extracted from the seeds of Dioclea wilsonii, is a metalloprotein with strong agglutinating activity against rabbit and ABO erythrocytes, inhibited by glucose and mannose. DwL was purified by affinity chromatography on a Sephadex G-50 column and ion exchange chromatography on a HiTrap SP XL column. SDS-PAGE revealed three electrophoretic bands corresponding to the α (25,634 ± 2 Da), β (12,873 ± 2 Da) and γ (12,779 ± 2 Da) chains. Protein sequencing was done by Tandem Mass Spectrometry. The primary sequence featured 237 amino acids and was highly homologous to other reported Diocleinae lectins. A complete X-ray dataset was collected at 2.0 ? for X-Man-complexed DWL crystals produced by the vapor diffusion method. The crystals were orthorhombic and belonged to the space group I222, with the unit-cell parameters a = 59.6, b = 67.9 and c = 109.0 ?. DWL differed in potency from other ConA-like lectins and was found to induce neutrophil migration in rats, making it particularly useful in structural/functional studies of this class of proteins.     

A Three-Channel Spectrometer for Wide-Field Imaging of Anisotropic Plasmonic Nanoparticles

A three-channel spectrometer (3CS) based on a commercial digital camera was developed to distinguish among tens of large (>100 nm), anisotropic plasmonic particles with various shapes, orientations, and compositions on a surface simultaneously. Using band pass filters and polarizers, the contrast of 3CS images could be enhanced to identify specific orientation and composition characteristics of gold and gold-silver nanopyramids and as well as the direction of the longest arm of gold nanostars.